Several methods are known for recovering gallium from aluminate liquors. Nowadays the "direct" recovery processes are generally used. Such "direct" processes are e.g. the mercury-pool cathode process (disclosed in Hungarian Pat. No. 145 729 and U.S. Pat. No. 2,793,179), electrolysis accomplished by using a liquid gallium cathode (disclosed in French Pat. No. 1 418 513) or by using a solid cathode (described in Hungarian Pat. No. 156 992 and U.S. Pat. No. 3,677,918), extraction with organic solvents (disclosed in Hungarian Pat. No. 164 521) and cementation by gallium (described in U.S. Pat. No. 3,988,150, USSR Pat. No. 263 154, 329 792 and 510 848).
The methods for recovering vanadium from alumina factory aluminate liquors are particularly based on crystallization. Such methods are disclosed e.g. in the following publications: Osvald, Z., Skuteczky, E., Zambo, J., Toth, B: Femipari Kutatointezet Kozlemenyei [Proceeding of the Metallurgical Industry Research Institute, published in Hungary], V., 53-62, (1961): Tarasenko, V. Z., Zazubin, A. I., Ponomarev, V. D., Baespalov, E. N.: Trudi Inst. Met. i Obogashch. Akad. Nauk. Kaz. SSR, 27, 66-74, (1968), Juhasz, A: Kohaszati Lapok [Metallurgical Periodicals, published in Hungary], 4, 161-168, (1958). Chemical and electrochemical reduction methods are also used; such methods are disclosed e.g. in U.S. Pat. No. 3,677,918 and USSR Pat. No. 431 752, and in the following publications: Zazubin, A. I., Bocskarev, B. A., Romanov, G. A.: Trudi Inst. Met. i Obogashch. Akad. Nauk. Kaz. SSR., 27, 79-85, (1968), Slavina, E. L., Ivanova, G. A.: Ibid., 17, 20-26, (1966).
A method suitable for recovering molybdenum from alumina factory aluminate liquor is not yet known.
Each of the mentioned processes, although several of them are used in factories even now, has certain technical imperfections. For recovering gallium the industrial aluminate liquor must always be subjected to a preliminary purification and the recovering process is accomplished by using poisonous or expensive reagents (e.g. aluminum, organic extracting agents). For recovering vanadium the investment in the heating and cooling systems is high, and the need for special chemicals results in a high production cost. The primary disadvantage of each known recovery process lies in the fact that the sufficiency of these processes depends mainly on the technical circumstances of alum earth processing (e.g. presence of organic materials, other inorganic impurities, concentration rates), and for this reason such processes must be adapted to the particular aluminate liquor.